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Jul 30, 2011, 08:25 AM
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JIMA's Avatar
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What is the difference between a UBEC and an SBEC and just a BEC?


My understanding is that for safety sake on larger airplanes it is a good Idea to add a UBEC/SBEC/BEC to isolate the speed controller and motor from the power to the receiver just in case the ESC or Motor has a melt down and you can still power the servos. But I dont know the difference between a UBEC or a SBEC or a plain ol BEC. Nor the advantage to either.

Can someone help me out with this?


Thanks
Jim
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Jul 30, 2011, 09:43 AM
Jack
jackerbes's Avatar
The various things you ask about have been used as model names in the past (UBEC for the Ultimate BEC for example), in other cases the same terms are used to simplify these kinds of discussions.

It is fair to assume that "BEC" started when it came into use as a component of the ESC. It would probably be more accurate to call the lead that comes from the ESC the "throttle lead/battery eliminator circuit" but that is a lot of extra typing and speaking.

So there really two major types of BEC's. Those would the internal BECs that are built in to an ESC and the external BECs that are not built in to an ESC.

I have been told that I cannot or should not refer to an external BEC as a UBEC because that is a trademarked model name, and if there is a Super BEC I suppose that would rule out SBEC...

I generally refer to a BEC only as a separate device as an external BEC to eliminate confusion.

Jack
Jul 30, 2011, 10:12 AM
An itch?. Scratch build.
eflightray's Avatar
There is a thread down in the 'Similar Threads' list, (just scroll down to see them).

The bottom one - BEC, SBEC & UBEC Differences Between Them has a good reply in post #3.

Basically SBEC and UBEC using a switching voltage regulator, and BEC uses a linear regulator, (not quite so efficient).
Jul 30, 2011, 11:07 AM
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Wintr's Avatar
Quote:
Originally Posted by eflightray
... and BEC uses a linear regulator, (not quite so efficient).
Not only less efficient, but the number of servos it will support drops as the battery voltage goes up.
Jul 30, 2011, 09:02 PM
//////////
coriolan's Avatar
Quote:
Originally Posted by Wintr
Not only less efficient, but the number of servos it will support drops as the battery voltage goes up.
Because they are less efficient and convert the excess voltage as heat the larger the difference is between Vin and Vout. A switching supply doesn't "waste" that differencial voltage.
Last edited by coriolan; Jan 22, 2012 at 05:24 PM. Reason: "G" for "V" in voltage!
Jan 22, 2012, 01:13 AM
sloper dude
Jeffrito's Avatar
Quote:
Originally Posted by eflightray

Basically SBEC and UBEC using a switching voltage regulator, and BEC uses a linear regulator, (not quite so efficient).
There is so much nonsense here.

A: SBEC, UBEC, BEC can all be internal or external.

B. UBEC is/was a brand name, Universal BEC, but besides that you will see BEC and UBEC used interchangeably. They are both LINEAR, and the input voltage is more limited than with an SBEC. They generate more heat the more voltage is supplied to them, which limits their usefulness.

C. SBEC is a switching BEC, which when it is integral with an ESC generally comes with better ESC's.

D. Opto ESC's do not come with a S/U/BEC. You will need to supply a separate one, hopefully an SBEC.

E. Your computer uses a switching power supply, which weighs far less than a linear PS, creates less heat, and is more efficient.
Jan 22, 2012, 03:20 AM
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scirocco's Avatar
Quote:
Originally Posted by Jeffrito
There is so much nonsense here.

A: SBEC, UBEC, BEC can all be internal or external.

B. UBEC is/was a brand name, Universal BEC, but besides that you will see BEC and UBEC used interchangeably. They are both LINEAR, and the input voltage is more limited than with an SBEC. They generate more heat the more voltage is supplied to them, which limits their usefulness.

C. SBEC is a switching BEC, which when it is integral with an ESC generally comes with better ESC's.

D. Opto ESC's do not come with a S/U/BEC. You will need to supply a separate one, hopefully an SBEC.

E. Your computer uses a switching power supply, which weighs far less than a linear PS, creates less heat, and is more efficient.
Jeffrito,

I'm afraid if you're going to refer to information as rubbish, you're going to need to get your facts straight. In this case, you are dead wrong with reference to the UBEC. The UBEC, in fact Ultimate BEC, not Universal BEC was developed by Jeff Meyers' Kool Flight Systems, and was in fact one of the first commercially available external SWITCHING BECS, developed 2002. I have 2. Here's the original product announcement following testing since Mar 2002. It was already being abbreviated to UBEC by the time it was released commercially. Photo and description here. It is most definitely a switching voltage regulator, just like in your PC, or any of the myriad of cool running switching power supplies for electronics that run cool unlike their transformer predecessors.

Like may other trade names for the first of a new product, the brand abbreviation UBEC has become synonymous with an entire class of external switching regulators, and while there could be some external BECs called UBECs that are not switching, BEC and UBEC in my experience since I bought some of the earliest UBECs have not been used interchangeably, with UBEC clearly understood as a switching regulator.

Now I'm into speculating, but it is possible that the term SBEC came into use because, a) UBEC is a brand name, and b) as an abbreviation of switching BEC it is more descriptive.
Jan 22, 2012, 04:10 AM
Registered User
I too have got a couple of genuine UBECs -- been using them since 2005. I've also got one "Super BEC" (can't remember the manufacturer), which also calls itself "SBEC", so maybe SBEC is also a registered trade name.

Anyway, as scirroco has said, UBEC and SBEC these days are generically used to mean the BEC is a switching one, rather than a linear one. With Chinese goods though, it's always good to read the small print, for I think I remember seeing a spec for an ESC that mentioned "SBEC", but when I read further I saw that it was linear.

Linear BECs, because they shed the excess volts as heat, are generally limited to use with maximum 3S battery and 4 standard servos, or 4S battery and 3 standard servos. Switching BECs reduce the voltage by switching on and off several thousand times per second, so don't generate so much heat and can be made to almost whatever spec the manufacturer wants.
Jan 22, 2012, 05:12 AM
fmw
fmw
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fmw's Avatar
Be sure you spend the money to get switching BEC's whether internal or external. All will be better if you do.
Jan 22, 2012, 05:52 AM
ancora imparo
jj604's Avatar
Not exactly all.

Linear BECs do have one advantage which may be useful in some circumstances. They generate much less electrical noise than switching BECs. I think most people would also regard them as more reliable than switchers.

In most cases however the greater efficiency of the switching BEC and its ability to operate over a wider voltage range and higher currents are more important.
Quote:
Originally Posted by fmw
Be sure you spend the money to get switching BEC's whether internal or external. All will be better if you do.
Jan 22, 2012, 07:00 AM
Registered User
If my understanding of electronics is correct, linear BECs are much simpler circuits that switching ones, with less components, so theoretically should be more reliable than the switching ones.

But I suspect that in practice the risk of failure by overheating outweighs that theoretical advantage.

The smaller amount of electrical noise with linear BECs is also probably theoretically true, but with my first 35MHz electric models I had to go from a Jeti ESC with built-in BEC (5 years ago, and not one of the Spin series, so I'm pretty sure it was a linear BEC) to a Jeti opto ESC and separate NiMh receiver battery in order to eliminate interference problems. Now I use 2.4GHz and stand-alone switching BECs (UBEC, SBEC, and Hyperion Cool BEC) and interference is not a problem.


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